Merge tag 'fs.idmapped.v5.15' of git://git.kernel.org/pub/scm/linux/kernel/git/braune...
[linux-2.6-microblaze.git] / arch / arm / crypto / curve25519-glue.c
1 // SPDX-License-Identifier: GPL-2.0 OR MIT
2 /*
3  * Copyright (C) 2015-2019 Jason A. Donenfeld <Jason@zx2c4.com>. All Rights Reserved.
4  *
5  * Based on public domain code from Daniel J. Bernstein and Peter Schwabe. This
6  * began from SUPERCOP's curve25519/neon2/scalarmult.s, but has subsequently been
7  * manually reworked for use in kernel space.
8  */
9
10 #include <asm/hwcap.h>
11 #include <asm/neon.h>
12 #include <asm/simd.h>
13 #include <crypto/internal/kpp.h>
14 #include <crypto/internal/simd.h>
15 #include <linux/types.h>
16 #include <linux/module.h>
17 #include <linux/init.h>
18 #include <linux/jump_label.h>
19 #include <linux/scatterlist.h>
20 #include <crypto/curve25519.h>
21
22 asmlinkage void curve25519_neon(u8 mypublic[CURVE25519_KEY_SIZE],
23                                 const u8 secret[CURVE25519_KEY_SIZE],
24                                 const u8 basepoint[CURVE25519_KEY_SIZE]);
25
26 static __ro_after_init DEFINE_STATIC_KEY_FALSE(have_neon);
27
28 void curve25519_arch(u8 out[CURVE25519_KEY_SIZE],
29                      const u8 scalar[CURVE25519_KEY_SIZE],
30                      const u8 point[CURVE25519_KEY_SIZE])
31 {
32         if (static_branch_likely(&have_neon) && crypto_simd_usable()) {
33                 kernel_neon_begin();
34                 curve25519_neon(out, scalar, point);
35                 kernel_neon_end();
36         } else {
37                 curve25519_generic(out, scalar, point);
38         }
39 }
40 EXPORT_SYMBOL(curve25519_arch);
41
42 void curve25519_base_arch(u8 pub[CURVE25519_KEY_SIZE],
43                           const u8 secret[CURVE25519_KEY_SIZE])
44 {
45         return curve25519_arch(pub, secret, curve25519_base_point);
46 }
47 EXPORT_SYMBOL(curve25519_base_arch);
48
49 static int curve25519_set_secret(struct crypto_kpp *tfm, const void *buf,
50                                  unsigned int len)
51 {
52         u8 *secret = kpp_tfm_ctx(tfm);
53
54         if (!len)
55                 curve25519_generate_secret(secret);
56         else if (len == CURVE25519_KEY_SIZE &&
57                  crypto_memneq(buf, curve25519_null_point, CURVE25519_KEY_SIZE))
58                 memcpy(secret, buf, CURVE25519_KEY_SIZE);
59         else
60                 return -EINVAL;
61         return 0;
62 }
63
64 static int curve25519_compute_value(struct kpp_request *req)
65 {
66         struct crypto_kpp *tfm = crypto_kpp_reqtfm(req);
67         const u8 *secret = kpp_tfm_ctx(tfm);
68         u8 public_key[CURVE25519_KEY_SIZE];
69         u8 buf[CURVE25519_KEY_SIZE];
70         int copied, nbytes;
71         u8 const *bp;
72
73         if (req->src) {
74                 copied = sg_copy_to_buffer(req->src,
75                                            sg_nents_for_len(req->src,
76                                                             CURVE25519_KEY_SIZE),
77                                            public_key, CURVE25519_KEY_SIZE);
78                 if (copied != CURVE25519_KEY_SIZE)
79                         return -EINVAL;
80                 bp = public_key;
81         } else {
82                 bp = curve25519_base_point;
83         }
84
85         curve25519_arch(buf, secret, bp);
86
87         /* might want less than we've got */
88         nbytes = min_t(size_t, CURVE25519_KEY_SIZE, req->dst_len);
89         copied = sg_copy_from_buffer(req->dst, sg_nents_for_len(req->dst,
90                                                                 nbytes),
91                                      buf, nbytes);
92         if (copied != nbytes)
93                 return -EINVAL;
94         return 0;
95 }
96
97 static unsigned int curve25519_max_size(struct crypto_kpp *tfm)
98 {
99         return CURVE25519_KEY_SIZE;
100 }
101
102 static struct kpp_alg curve25519_alg = {
103         .base.cra_name          = "curve25519",
104         .base.cra_driver_name   = "curve25519-neon",
105         .base.cra_priority      = 200,
106         .base.cra_module        = THIS_MODULE,
107         .base.cra_ctxsize       = CURVE25519_KEY_SIZE,
108
109         .set_secret             = curve25519_set_secret,
110         .generate_public_key    = curve25519_compute_value,
111         .compute_shared_secret  = curve25519_compute_value,
112         .max_size               = curve25519_max_size,
113 };
114
115 static int __init arm_curve25519_init(void)
116 {
117         if (elf_hwcap & HWCAP_NEON) {
118                 static_branch_enable(&have_neon);
119                 return IS_REACHABLE(CONFIG_CRYPTO_KPP) ?
120                         crypto_register_kpp(&curve25519_alg) : 0;
121         }
122         return 0;
123 }
124
125 static void __exit arm_curve25519_exit(void)
126 {
127         if (IS_REACHABLE(CONFIG_CRYPTO_KPP) && elf_hwcap & HWCAP_NEON)
128                 crypto_unregister_kpp(&curve25519_alg);
129 }
130
131 module_init(arm_curve25519_init);
132 module_exit(arm_curve25519_exit);
133
134 MODULE_ALIAS_CRYPTO("curve25519");
135 MODULE_ALIAS_CRYPTO("curve25519-neon");
136 MODULE_LICENSE("GPL v2");